The question of how to feed cities may be one of the biggest contemporary questions, yet it's never asked: we take for granted that if we walk into a store or a restaurant, food will be there, magically coming from somewhere. Yet, think of it this way: just in London, every single day, 30 million meals must be provided. Without a reliable food supply, even the most modern city would collapse quickly. And most people today eat food of whose provenance they are unaware.

Architect and author Carolyn Steel uses food as a medium to "read" cities and understand how they work. In her book Hungry City she traces -- and puts into historical context -- food's journey from land to urban table and thence to sewer. Cities, like people, are what they eat.